Are My Calibration Standards Still Good?

Calibration Standards Shelf Life

We provide buffers and calibration solutions for our water quality meters that have shelf lives or expiration times that should be adhered to.  Since your data is only as good as your calibration, we recommend understanding the expiration dates of the solutions you use. pH Sensor In Buffer Solution

(Expiration times for unopened/unmixed solutions are from the date of manufacture, not the date of purchase.  Expiration dates are clearly labeled on the bottles.)


  • Unopened - Glass Quarts = 1 year
  • Unopened - Plastic Pints = 18 months
  • Opened = 1 month

Zobell Solution (used for ORP/Oxidation Reduction Potential)

  • Unmixed = 5 years
  • Mixed = 6 months

pH Buffers

  • Unopened = 2 years
  • Opened = 2 months

Confidence Solution (verifies pH, ORP and conductivity)

  • Unopened = 2 years
  • Opened = 3 months


  • Unopened = 1 year
  • Opened = 6 months


  • Unopened = 18 months
  • Opened = 6 months


  • Unopened = 1 year
  • Opened = 6 months

Dissolved Oxygen Probe Electrolyte Solution

  • Unmixed Crystals = No Stated Expiration
  • Mixed Solution = 1 year

Platinizing Solution (used on conductivity cells)

  • No Stated Expiration

TruLine ISE Calibration, ISA, and Filling Solutions

  • Unopened = 15 months
  • Opened = 6 months

NOTE: Expiration times for unopened/unmixed solutions are from date of manufacture, no date of purchase. Expiration dates are clearly labeled on the bottle. TruLine solutions are for the TruLine laboratory ISEs.

Download Solutions Expiration Guide



Additional Blog Posts of Interest:

YSI Expert Tip 5 of 7 - Get Your Water Quality Sonde Field Ready

The Ultimate pH Primer - Are You Familiar with Hydrogen?

Extend the Life of Your pH Electrode in 3 Practical Steps

A Step-by-Step Guide to Installing Stretch-Over DO Membranes

1 Responses to this article

How do you get rid of expired solutions, are they safe to throw in the toilet?


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